Well you add the seeds, a liquid like water, and hook it up to a power source. Then it pretty much runs on its own. You can come back later and empty out the whatever the crop yields. The thing uses up the water so you need to put a large amount in to keep it running over a long time (one quick trip to an ocean should last you for days). An added side feature is that most crops grow much faster then normal. This is very useful for the really slow growing crops. I tend to only have a small number going at any one time and change out crops as I need them (after you have a few hundred of a crop you tend not to need much more of them for a while). For things that I need a large number of I just use the old fashion farms since they are cheaper and faster to scale up to insane levels.